ORGANIC ANALYSIS 357 INORGANIC ANALYSIS. Precipitant for Ammonia. (Substitute for Nessler’s Reagent.) S. S. Graves. (J. Amer. Chem. Soc., 1915, 37, 1171-1181.)-The alkaline solution of the double salt of mercuric and sodium chloride8 gives a white precipitate with ammonia, analogous to the coloured compound formed with Nessler’s reagent, but which is358 ABYTKACTS OF CHEMICAL PAPERS considerably more stable.For the estimation of minute quantities of ammonia the degree of turbidity produced is determined by means of tho nephelometer, for which purposg agglutination of the precipitate must be prevented for a suficient length of time by the presence of a protective colloid--e.g., soluble starch. For the prepara- tion of the reagent, water free from ammonia, obtained by distilling tap-water acidified with sulphuric acid, is employed.To 80 grms. of sodium chloride are added 130 C.C. of water and 100 C.C. of a cold saturated solution of mercuric chloride. When the salt is practically all dissolved, 70 C.C. of a saturated solution of lithium carbonate are added slowly while shaking, so that no mercuric oxide forms on the sides of the flask.The solution is usually cloudy, and should be filtered clear after shaking with a little talc powder. I t may be used at once, and is permanent in stoppered bottles. The starch solution should be freshly prepared eaoh day by boiling 1 grm. of soluble starch with water and diluting to 100 C.C. The standard solution of ammonium sulphate is prepared by mixing 10 c,c. of a solution contain- ing 100 mgrms. of the pure salt per litre with 10 C.C.of a solution of potassium sulphate (75 grms. per litre) and making up to 100 C.C. The standard turbidity for the nephelometer is usuallymade up with 10 C.C. of this ammonium sulphate solu- tion, 15 C.C. of a 0.003 per cent. solution of starch and 5 C.C. of the reagent. Details of the nephelometric instrument, calculations and manipulation, have been described by Kober (ANALYST, 1913, 38, 571).Determinations carried out with known quantities of ammonia have shown that the precipitation is complete, and that the method is available for the estimation of ammonia either alone or in presence of organic matter. It is also available for the estimation of nitrogen by the Kjeldahl method without the necessity of distilling over the ammonia.I n the latter case copper sulphate must not be used as catalyst, and some caution is required in neutralising to avoid any large exoess of alkali hydroxide. In all experiments controls should be carried out on the water used as well as on the reagents. J. F. B. Inter-Relationships between the Constituents of Basic Slag. S. H. Collins and A.A. Hall. ( J . SOC. Chnz. I d . , 1915, 34, 526-530.)-The results of analysis of a number of samples of basic slag are subjected to mathematical treat- ment, and although the probable error of the calculated coefficients of correlation is shown to be large, the fact that there is a fairly close correlation between citric solubility and lime content is brought out plainly. That citric solubility and fine- ness would be found to be correlated was to be expected, but that the lime content has more influence on citric solubility than has the fineness, a point established by these results, is more striking, especially as Robertson has shown (ANALYST, 1914,39, 146) that with some other materials than slag the lime content and citric solubility move in opposite directions.I t seems also established beyond doubt that both silica and magnesia tend to diminish the citric solubility. An attempt is also made to correlate some field results (yield of hay) with the constituents of the basic slag used as manure. The various slags were used in such quantity that the dressing of phosphoric anhydride per acre was the same in all experiments. The coefficient of correlation for any single constituent is very smallINORGANIC ANALYSIS 359 -in no case twice as great as the probable error attaching to it, and in many cases its sign is in doubt.On the other hand, when the results are plotted on a system of rectangular co-ordinates some suggestive figures result. The figures are irregular, but indicate very strongly that for the soils on which these experiments were made slag of average quality is best, the curves with crop yields for ordinates and per- centages of lime, iron, or oxide of manganese as abscisst-e, showing maxima at about the mean value for these percentages.The conclusion drawn is that a certain balance of the minor constituents of slags is desirable, and that for the particular soils experimented with, the analyses of which are given, this balance is attained .in the average steel works, slags most closely approximating average composition giving the best results, and slags abnormal in any respect less satisfactory ones. I t is pointed out that this conclusion does not necessarily extend to soils of different character. I t is remarkable that the curve connecting crop yield with citrate solubility also shows a maximum at about the mean value for the latter.G. C. J. Estimation of Boron in Iron. J. M. Lindgren. (J. Amer. Chem. Soc., 1915, 37, 1137-1139.)--For the estimation of small proportions of boron in iron, Gooch’s method, by the distillation of the methyl ester, was found impracticable, but good results were obtained by following the principles of the method described by Wherry (ANALYST, 1909, 34, 34).Two to three grms. of iron are dissolved in a mixture of 10 C.C. each of nitric acid (sp. gr. 1.4), hydrochloric acid (sp. gr. 1.2), aud water, the product is then neutralised with calcium carbonate. Certain precautions are neces- sary to prevent the separation of the precipitate in a colloidal form. The volume of the liquid is approximately 30 C.C.; to this is added, all at once, about double the quantity of dry calcium carbonate necessary for complete neutralisation, and the mass is vigorously agitated until it forms a pasty golid; hot water is then poured in, and the ferric hydroxide should separate as a dark brown, granular Precipitate. The whole is boiled with 250 to 300 C.C.of water under a reflux condenser for at least thirty minutes to insure complete expulsion of carbonic: acid. Before filtering, the liquid is mixed with a considerable quantity of washed asbestos fibre, which has been digested for several hours on a steam-bath with dilute hydrochloric acid. The washed asbestos is added moist to the iron precipitate, using about 50 C.C. of the pulp, and the mixture boiled for a few minutes, then filtered on a Buchner funnel through a double thickness of paper.The solid matter is washed with boiling water, and the filtrate again brought to the boil by closing the flask and exhausting. After the addition of phenolphthalein a pink colour is established with sodium hydroxide, 1 grm. of mannitol is added, and the liquid titrated until the pink colour reappears. The titration should be controlled by a blank experiment with pure iron treated in the same manner.Estiiiiations have shown that the whole of the boron, in mixtures containing from 0.04 to 0.85 per cent., can thus be estimated with satis- factory accuracy. J. F. B. Battery Assay of Copper. W. B. Price and Others. (J. Ind. and E’ng. Chem., 1915, 7, 546-547.)-This is a report of the Sub-Committee on Methods of Analysis of360 ABSTKACTd OF CHEMICAL YAl'EltS Nan-Ferrous Alloys of the American Chemical Society, and embodies methods generally accepted in the United States for standard analysis by both producers and Consumers of copper and copper products.SampZing.-Detailed directions are given, the most important points being that ingots should be drilled right through and slowly enough to prevent oxidation.The material removed by the first twist of the drill is rejected, as it is desired to exclude the superficial layer of oxide from the sample. No lubricant should be used, but the ifigot may need to be cleaned with ether before starting. The drillings are sifted on a @mesh (per lineal inch) sieve to remove material which has been ground between the drill and the hole, are freed from iron by means of a mignet, and preserved in air- tight bottles.WeQhts and Weighings.-Detailed directions are given to insure the elimination of errors not tolerable in an assay where an accuracy of 1 in 10,000 is demanded. Electrodes.-The cathode is a sheet of platinum, 5 x 10 cm., bent to form an open cylinder-that is to say, the edges are not welded. The stem is riveted and soldered with gold to the middle of the sheet.The anode is made from 1 mm. platinum wire, formed into a helix of seven turns, with a diameter of 12-13 mm. and 8 height of 38 mm., the stem being straight and 125 mm. long. Assay of Ebctrolytic and Low Resistance Copper.-The method described is essentially that of Heath (ANALYST, 1911, 36, 172).I t is to be used for all such grades of copper as are included in the specifications of the Anierican Society for Testing Materials as Electrolytic and Low Resistance Lake Copper. Silver is deposited with copper, an arrangement that works well, provided the silver content does not exceed 100 ozs. per ton. The drillings (5 grms.) are dissolved in 42 C.C.of a stock solvent, made by mixing water, sulphuric and nitric acids in the proportiom 25 : 10 : 7 by volume. The beakers used are 100 to 125 mm. high and 55 mm. in diameter at the base, and hold 225 to 300 C.C. When action has nearly ceased, the beakers are placed on a steam-bath so that the contents may attain a temperature of 80" to 90' C., and left there until solution is complete and red fumes have disappeare'd.The cover and sides of the beaker are washed down, and the solution diluted to 150 C.C. and electrolysed overnight with a current of 1 ampere, which will require about 10 volts if the a,ssays are arranged in parallel. After fifteen hours, cover- glasses, beakers, and electrodes are washed down, and the current reduced to 0.6 ampere. At the first sign of gas evolution (the assay should finish if possible without decided gas evolution) the current is reduced to 0-4 ampere, and 1 C.C.of the electrolyte tested with 2 to 3 drops of fresh hydrogen sulphide water. If any discoloration occurs, electrolysis is continued until a further test shows no discolora- tion. Without interrupting the current, the electrolyte is syphoned off, the beakers being simultaneously filled with water.The cathodes are quickly removed, immerrsed once in water, twice in alcohol, twirled to centrifuge off moat of the alcohol, the rest of the latter ignited, and the cathodes cooled and weighed. Heath's rapid method (Zoc. cit.) may be used by those possessed of the necessary apparatus and experience, but rapid methods require considerable experience before satisfactory results can be obtained, and in any case they require more of the analyst's time.Duplicate assays by the slow method above described should not differ by more than 0.015 per cent.INORGANIC ANALYSIS 361 Assay of Low Grade or Casting Copper.-The following methods are recommeuded for the assay of all grades of copper not included in the specifications of the American Society for Testing Materials.I n presence of very small quantities of impurity, the assay is carried out as already described, the copper redissolved in 42 C.C. of the stock solvent diluted with water, and the copper redeposited as described. A method of more general application consists in dissolving the drillings as described, evaporating until all nitric acid is expelled, redissolving in water, adding 3 c.0.of ferric nitrate solution (1 C.C. =0*01 grm. iron), precipitating the iron from the hot solution with ammonia, and filtering and washing the filter. The precipitated hydroxide is twice redissolved in sulphuric acid and reprecipitated, the filtrates being added to the main copper solution, which is concentrated to convenient bulk, made acid with sulphuric acid, and electrolysed after addition of 2 C.C.of nitric acid. A third method is specially suited for the assay of copper containing only traces of antimony or bismuth, but sufficient selenium or tellurium to interfere. The drillings are dissolved as described, and the solution evaporated until fumes appear or the residue is white.The latter is redissolved in 60 C.C. water, the solution heated to boiling and saturated for ten minutes with sulphur dioxide, removing the source of heat when the gas is started. After a few hours, the solution is decanted through a filter and the precipitate washed with hot water. The filtrate is boiled to expel most of the sulphur dioxide, whilst the filter is ignited to volatilise selenium and tellurium, the oxidised residue being dissolved in 2 C.C.of nitric acid and added to the main solution. This is then electrolysed. Copper high in arsenic, but comparatively free from other impurities, may be assayed successfully by the method given for low resistance copper without further modification than the use of 60 C.C. of stock solvent instead of the usual 42 C.C.G. C. J. New Test for Copper. W. G. Lyle, L. J. Curtman, and J. T. W. Marshall. (J. Amer. Chem. SOC., 1915, 37, 1471-1481.)-An aqueous solution of normal amino- caproic acid is an exceedingly sensitive reagent for the detection of copper, a solution containing 0-004 mgrrn. of copper in 1 C.C. giving an unmistakable precipitate within five or ten minutes.The sensitiveness is much less in presence of even traces of mineral acid, such as are liberated when the reagent is added to solutions of the sulphate, etc., of copper, and the figure given above is the results of experiments with 1 C.C. of copper solution, 1 C.C. of 40 per cent. sodium acetate, and 1 C.C. of a saturated solution (about 0.6 per cent.) of the reagent. Mercury and zinc are the only other common metals that yield difficultly soluble arninocaproates, but the necessity of using sodium acetate in amount sufficient to neutralise any mineral acid present introduces difficulties when silver, bismuth, antimony, tin, iron, aluminium, chromium, nickel, or cobalt are present, The greater part of the paper ie occupied with the detailed description of means whereby all these metals can be eliminated without co-precipitation of the trace of copper to be detected.Ammonium salts, glycine, synthetic leucine, casein and citrates inhibit the reaction, but tartrates in relatively large amount do not interfere. G. C. J.362 ABSTItAC’I’S OF CIIEMJCAT, I’APEKS Estimation of Copper in Commercial Copper Sulphate. G. Incze. (Zeitsch.anal. Chcm., 1915, 54, 252-255.)--The copper sulphate solution is treated with an excess of thiosulphate solution containing thiocyanate ; the copper is thus reduced and precipitated as cuprous thiocyanate, and the excess of the added thio- sulphate is then titrated. 8CuSO,+ Na3S,O3 + 5H,O = 4Cu,S04+ Na,S04 + 5H,S04, and The thiosulphate solution used is propared by dissolving 19.878 grms.of the salt and 8 grms. of ammonium thiocyanate in 1 litre of water ; the iodine solution employed for titrating the excess of the thiosulphate contains 1-0178 grms. of iodine and 5 grms. of potassium iodide per litre. One C.C. of the thiosulphate solution should require exactly 10 C.C. of the iodine solution. Ten grms. of the copper sulphate are dissolved and diluted to 500 c.c.; 50 C.C.of this solution are treated with 52 C.C. of the thiosulphate solution, starch solution is added, and the mixture titrated with the iodine solution. The percentage quantity of copper sulphate in the sample is found by subtracting 20 from the number of C.C. of iodine required for the titration and dividing tho remainder by 5. The presence of iron salts in the copper sulphate does not interfere with the estimation.w. P. s. The reactions proceed according to the equations- 4cU,so4+ 8NH4CNS = 8CuCNS+ 4(NH4),S04. Analysis of Hypochlorite Solutions. IBI. L. Griffin and J. Hedallen. (J. SOC. Chem. Ind., 1915, 34, 530-533.)--For the purpose of an investigation of the factors influencing the stability of hypochlorite solutions, the results of which are published in this paper, the authors found it necessary to submitl to a critical examination the most approved methods of determining available chlorine.Bunsen’s original method-delivery of the bloach liquor into an excess of potassium iodide, addition of acetic acid, and titration of the liberated iodine with thiosulphate-was found to be the most exact as well as the quickest.For purposes of works control, Penot’s method--titration of a known volume of the bleach with alkali arsenite, using iodide and starch a8 indicator-and Mohr’s more convenient modification of it-adding excess of arsenite, and titrating the excess with standard iodine-are more economical of iodide, and make use of solutions the titer of which remains constant for long periods, but neither method is exact.Under the conditions obtaining in the authors’ experiments, the results by either method were uniformly 0-6 per cent. low, duplicates agreeing well. For some technical purposes this error would be tolerable ; whilst if greater accuracy is required, the correction to be applied to the results can be readily determined, once for all, in a, given laboratory by comparing a few results with duplicates obtained by Bunsen’s method.I t is probable that the results are much less influenced by small changes in the experimental conditions than has sometimes been alleged, and that the correction is never very different from 0.6 per cent. In particular it has been alleged that the results are dependent on tho time occupied in performing the titra- tion, and-in Mohr’s method-on the excess of arsenious acid employed.The authors, experimenting over a wide range, were unable to get any evideiic~ of such dependence. G. C. J.INORGANIC ANALY8IS 363 Valuation of Commercial Arsenate of Lead. R. H. Robinson and H. V. Tartar. (J. Ind. and Eng. Chem., 1915, 7, 499-502.)-The presence of water- soluble compounds of arsenic in arsenical insecticides is objectionable, as such compounds are injurious to foliage, and the laws of the United States set a limit (0.75 per cent. As,O,) to the amount that may be present in arsenate of lead sold for agricultural purposes.As in most cases where a soluble constituent has to be estimated in admixture with a much larger quantity of insoluble material, and especially in the administration of a penal statute, it was necessary to prescribe a, particular method of analysis.The authors show that the present official method does not extract as much as 70 per cent. of the soluble compounds of arsenic, and describe a method which gives results on the average 50 per cent. higher than those yielded by the official method. I t is also shown that the new method does actually extract soluble compounds, and that the higher results are not due to hydrolysis or other chemical action.The new method consists in macerating the sample (5 grms.) with water, transferring the mixture to a filter, and washing it with nearly 1,000 C.C. of hot water free from carbon dioxide and ammonia. The soluble arsenate is then estimated in an aliquot portion of the filtrate in any convenient manner.G. C. J. Volumetric Estimation of Nickel. G. Zuccari. (Amali Chim. AppZic., 1915, 3, 277-279.)-The solution of the nickel salt is slowly titrated with a solution of sodium nitroprusside (50.771 grms. per litre ; 1 C.C. =0.01 grm. Ni) with constant agitation, until the compound NiFe(CN),(NO) has been completely precipitated.The end of the reaction is indicated by a spotting test of the filtered liquid with sodium sulphide, a slight violet fugitive coloration being obtained when all the nickel has been precipitated. I t is essential that the solution should not contain less than 1 to 1.5 per cent, of nickel, and that no trace of the precipitate should pass through the filter-paper in the spotting test.To insure complete precipitation of nickel, the test should be repeated after the liquid has stood for five minutes. The titra- tion is preferably done in acid solution. The method is applicable to the direct deter- mination of nickel in its common salts, even in the presence of other metallic salts auch as those of ferric iron, zinc, tin, aluminium, lead, manganese, etc. Nickel nitroprusside is very soluble in ammonia, forming a yellowis h-brown solution.It gives a, lemon yellow compound with potassium hydroxide, and is soluble in potas- sium cyanide solution. The corresponding cobalt salt, CoFe(CN),(NO), is rose- coloured and insoluble in acids. I t is insoluble in ammonia, but combines with it to form a brown compound. Ammonia can therefore be used to separate it from the nickel salt.The volumetric method does not give good results with cobalt, owing to the solubility of the precipitate being too great. C. A. M. Determination of Nitric Nitrogen in Soils. E. R. Allen. (J. Ind. a d Eng. Chem., 1915, 7 , 521-529.)-This paper is concerned only with the quantitative reduc- tion to ammonia of nitric nitrogen contained in aqueous solutions, which may also contain much organic matter of the type yielded to water by soils.The considera- tion of the extraction of nitrates from soils is deferred, as is consideration of the364 ABSTRACTS OF CHEMICAL PAPERS separation of the ammonia, nitric and organic nitrogen of soils. I n contradiction to Burgess (Univ. of California Publications in Agr. Sci., 1913, 1, No.4), the author confirms the older view that the aluminium reduction process, as applied to potable waters, breaks down utterly in presence of much organic matter of the type above referred to, 40 per cent., and even more, of the nitric nitrogen being unreduced. The method finally recommended depends on reduction by Devarda’s alloy, and is based on a study of two earlier methods, due to Mitscherlich (Landzo.Jahrb., 1909, 38, 279) and Valmari (Helsingfors dissertation, 1912). Both these authors used Devarda alloy, the former in strong, the latter in weak, alkaline solution. Mitscher- h h proved that reduction was complete under his conditions, and his apparatus eliminated errors due to the carrying over of alkaline spray which the rapid evolution of hydrogen tends to bring about.The use of strong alkali (4 to 5 - 2 9 , however, as used by Mitscherlich, makes it almost impossible to separate nitric from organic nitrogen ; hence the investigation of Valmari’s method. In absence of any consider- able quantity of organic matter, Valmari effected reduction in a solution no more alkaline than that resulting from the addition of a little magnesia (about i$m)* Under these conditions, the method yields excellent results, and Valmari’s simple apparatus is adequate, as the evolution of hydrogen is so slow that there is no danger of spray going over.In presence of much organic matter, however, Valmari found it necessary to add sodium hydroxide. He only made his solutions about &, but even this concentration revives the spray difficulty.With the provision of adequate means for dealing with this spray, the author finds this modification of Valmari’s method satisfactory. A higher concentration of alkali than & is unneces- sary, is more likely to bring about decomposition of organic nitrogenous compounds, and requires more Devarda metal to insure complete reduction. On the other hand, reduction is incomplete when the alkalinity is as low as ;a in presence of much organic matter.Reduction is effected in a 500 C.C. Kjeldahl flask, the stearn and ammonia, issuing from this being led up through a spray trap and down to the bottom of a round-bottomed 250-C.C. Jena flask containing 40 C.C. of water, a pinch of magnesia and of magnesium sulphate, and fitted with a double-bored rubber bung.Through the second hole in this bung issues a quartz tube bent twice at right angles, the distal limb dipping into 25 C.C. of standard acid and 60 C.C. of water contained in a 300 C.C. Jena Erlenmeyer flask. The distal end of thequartz tube, as well as that of the glass tube dipping into the scrubbing flask, terminates in a bulb-shaped enlargement, perforated with 1 mm.holes. The purpose of the magnesium sulphate in the scrubbing flask is to decompose any sodium hydroxide brought over as spray, d i d magnesium hydroxide being much less likely to go forward than sodium hydroxide. The scrubber and receiver being charged, 250 C.C. of the soil extract are placed in the Kjeldahl flask with 2 C.C. of 50 per cent. sodium hydroxide and boiled for thirty minutes to expel ammonia, mechanical loss of liquid being prevented by a, small f.unnel in the mouth of the flask.The contents of the flask are made up again to 250 C.C. with cold water and cooled. Devarda alloy (1 grm. of 60 mesh) and a small piece of paraffin are added, connection made with the rest of the apparatus, and distillation continued for forty minutes.No heat is applied to the contents of the The procedure recommended is as follows :INORGANIC ANALYSIS 365 scrubber. attaching to the measurement of the standard solutions. The =curacy of the method is limited only by the unavoidable error G. C. J. Permanganate and Iodimetric Estimation of Iodide in Presence of Chloride and Bromide. 0. L. Barnebey. (J. Amer. Chem. SOC., 1915, 37, 1496- 1507.)-In the original method of Pean de St. Gilles for titrating iodide in presence of chloride and bromide, with permanganate, the results are erroneous because of the liberation of free bromine or chlorine or formation of hypochlorous acid.The presence of manganese sulphate and phosphoric acid in the ferrous solution allows the removal of the excess of permanganate and manganese dioxide without liberation of bromine or chlorine from the halides, as well as insuring a correct permanganate titration of the excess of ferrous salt.Iodide can also be determined in presence of bromide and chloride by addition of potassium iodide to the final solution obtained by the modification of Pean de St. Gilles’s method outlined above, followed by titration of the liberated iodine with thiosulphate.The sample (0.05 to 5 grms. according to its probable content of iodide) ie dissolved in 100 C.C. of recently boiled water, I C.C. of sodium hydroxide is added, the mixture heated to boiling and kept hot and shaken, whilst standard perman- ganate or stronger) is added, 5 to 10 C.C. at a time, until a, permanent red or green colour is imparted to it.The contents of the covered flask are maintained just below boiling-point for five minutes, more permanganate being added and the solution reheated if the colour disappears. The solution is cooled, and to it is added, all at once with agitation, 15 C.C. of manganese solution (200 grms. manganese sul- phate crystals and 350 C.C. phosphoric acid of sp. gr. 1.7 per litre) and suficient standard ferrous sulphate to react with all the manganese dioxide and excess of permanganate and leave an excess of 10 to 15 C.C.As soon as the manganese dioxide has dissolved completely, the solution is diluted to 300 to 400 C.C. and titrated with permanganate. The percentage of iodide in the sample is calculated from the amount of permanganate required to oxidise it to iodate. For the iodimetric titration, a, few drops of ferrous sulphate are added to remove any excess of permanganate, 1 grm.of potassium iodide is added, and the liberated iodine is titrated with standard thiosulphate. The percentage of iodine in the original sample is then calculated from the amount of thiosulphate required to react with the iodine produced by the interaction of this amount of iodine, in the form of iodate, with excess of iodide.If the iodimetric method only is to be followed, naturally the strength of the permanganate and ferrous sulphate need not be known exactly. The two methods have about equal merit, except when applied to extremely small quantities of iodide, when the iodimetric method is preferable. G. C. J. Permanganate Estimation of Iron in the Presence of Fluorides.Analysis of Silicates and Carbonates for their Ferrous Iron Content. 0. I,. Barnebey. (J. Amer. Chem. Soc., 1915, 37,1481-1496.)-Dittrich and Leon- hard (ANALYST, 1912, 37,146) have shown that the uncertain end-point in the titra- tion of solutions obtained by treating silicate rocks with hydrofluoric acid may be366 ABSTRACTS OF CHEMICAL PAPERS overcome by addition to the solution of sulphuric acid, together with large quantities of precipitated silica and potassium sulphate.The author shows that sulphuric acid alone between the concentrations of F and 5N gives very satisfactory results. With less or more acid present, the pink tint of a fully titrated solution is less permanent. Freshly precipitated silica is useful, as is titanium dioxide, whilst acid sulphates act like sulphuric acid ; but the only neutral sulphates found effective were magnesium and ferric sulphates, the latter an inconvenient reagent because of its colour when added in excess, as is necessary.The most convenient reagent for arresting the tendency of the pink colour to disappear when the titration should be complete is boric acid, which has the added advantage that ferrous fluoborate is remarkably stable towards atmospheric oxygen (air bubbled through the solution for an hour does not lower its titer), whereag ferrous fluoride is very unstable.Moreover in presence of boric acid the customary manganese phosphate solutions may be used to counteract the influence of hydrochloric acid if simultaneously present, whereas in absence of boric acid either manganese salts or phosphates tend to make the end- point very uncertain if hydrofluoric acid is present, Notes are given on the solution of silicate rocks in a mixture of sulphuric and hydrofluoric acids under such conditions that ferrous salts are not oxidised, an operation requiring great care. The method is eseentially that of Cooke (Amer.J. Sci., 1867, [a], 44, 347). When decomposition is complete, the solution is diluted some- what with cold, recently boiled, distilled water, and an excess of solid boric acid immediately added. The subsequent titration with permanganate can then be conducted at leisure, after filtration from solid organic matter, if necassary. G. C. J. Estimation of Sulphuric Acid and Potassium, especially in Potash Salts.W. Vaubel. (Zeitsch. ofentl. Chem., 1914,20,426-434 ; 1915,21,1-6; through J. SOC. Chem. Ind., 1915, 34,658.)-The author recommends estimation of the sulphuric acid by the benzidine method and of potassium by the cobaltinitrite method. The acid sulphate solution is diluted till it contains 0.1 to 0-2 per cent. sulphuric acid, and precipitated with an equal volume of a solution of benzidine hydrochloride prepared by dissolving 6.7 grms.of the base in 20 C.C. of hydrochloric acid of sp. gr. 1.12, and diluting to 1 litre. The solution should not contain more than 10 mols. HCl, 15 mols. HN03, 20 mols. CH3C0,H, 5 mols. alkali salts, or 1 to 2 mols. ferric iron per mol. H,SO,; when one or more atoms of sulphur are present per atom of ferric iron, reduction to the ferrous state is not necessary.For the estimation of potassium Zaleski’s method (ANALYST, 1914, 39,47) is recommended, using a reagent prepared by pouring a solution of 30 grms. of cobalt nitrite in 1 litre of water and 250 C.C. of nitric acid of sp. gr. 1.2 into a solution of 300 grms. of sodium nitrite in 1 litre of water, the mixture being agitated, allowed to stand for twenty-four hours, and filtered. Precipitation of Phosphorus as Ammonium Phosphomolybdate in Presence of Sulphurie Acid.K. G. Falk and K. Sugiura. (J. Amer. Chem. Soc., 1915, 37, 1507-1515.)-A critical examination of Neumann’s method for theINORGANIC ANALYSIS 367 estimation of phosphorus in organic matter. Neumann (Zeitsch, Physiol. Chem., 1902, 37, 115 ; 1904, 43, 35) oxidised the material with sulphuric and nitric acids, and estimated the phosphoric acid by a method which was substantially that of Pemberton-namely, precipitation as ammonium phosphomolybdate, and titration of the washed precipitate with sodium hydroxide.Under some conditions Pemberton's method is exact, but it is well known that in presence of many substances (e.g., sulphuric acid) the composition of the molybdate precipitate varies with the concen- tration of these substances and other experimental conditions, so that in such circumstances accurate estimations can only be made by working the method as an empirical one (cf.ANALYST, 1914, 39,100). The present paper emphasises these facts, it being shown that precipitates obtained under Neumann's conditions always retain sulphate after washing until the wash-waters are neutral, that their exact composi- tion is also dependent on the concentration of the other constituents of the medium in which they are formed, and that consequently each analyst must determine the NaOH : P,O, factor corresponding to his own particular set of conditions.G . C. J. Estimation of Phosphorus Hydride. H. Reakleben. (Zeitschz. anal. Chem., 1915, 54, 241-252.) - For the gasometric estimation of phosphorus hydride in mixtures of this gas with hydrogen (such a mixture, for instance, as is obtained by the action of potassium hydroxide on phosphorus), the following solutions may be employed for absorbing the phosphorus hydrido : $ iodine solution, hypochlorite ~olution, hypobromite solution, concentrated potassium iodate solution, silver nitrate solution, mercuric chloride solution, and mercurous salt solutions.Equally accurate results are obtained by the use of chlorine water (this must not contain more than 0.16 per cent. of chlorine, or an explosion is liable to occur), saturated bromine water, acidified bromide-bromate solution, ammoniacal silver solutions, cuprous chloride solution containing hydrochloric acid, and acidified permanganate solution, but it is necessary to treat the residual hydrogen with a suitable reagent to remove volatile substances (chlorine, bromine, ammonia, etc.) introduced from the solutions.A mixture of phosphorus hydride and hydrogen may be stored over saturated sodium chloride for a long time without undergoing change ; this solution should be used in the measuring burette.w. P. s. Detection of Sodium. E. C. Mathers, C. 0. Stewart, H. V. Houseman, and I. E. Lee. (J. Amer. Chem. Soc., 1915, 37, 1515-1517.)-For many purposes the flame test for sodium is too sensitive. Nost other methods are troublesome. The method recommended depends on separation of potassium as perchlorate or fluoborate and detection of sodium by the insolubility of the fluosilicate in alcohol.An advantage of the method is that the previous separation of magnesium, a troublesome operation, is unnecessary. Lithium does not interfere. Pure perohloric acid is preferable to fluoboric acid for separating potassium, but, being more difficult to prepare, the UBB of the latter is recommended.Excess (about 35 grms.) of boric acid is added to 100 C.C. of 48 per cent. hydrofluoric acid in a lead or platinum dish, the mixture being tested with lead nitrate to insure absence of368 ABSTRACTS OF CHEMICAL PAPERS unchanged hydrofluoric acid. When cold, an equal volume of alcohol is added and enough hydrofluosilicic acid (see below) to precipitate any sodium which may have been present as impurity in the boric acid.Large excess of hydrofluosilicic acid must be avoided. Hydrofluosilicic acid is prepared by pouring hydrofluoric acid over excess of sand. At the end of some hours the solution is tested to insure absence of unchanged hydrofluoric acid, and diluted with an equal volume of alcohol. The reagents must be stored in wax, etc., receptacles, but do not noticeably etch test-tubes in the course of analysis.The solution to be tested, having been freed from all metals save magnesium and the alkali metals, is evaporated to dryness and the residue ignited to expel ammonium salts, which would interfere. The residue is dissolved in about ten times its weight of water, the solution mixed with an equal volume of alcohol and an excess of the fluoboric acid solution. The potassium fluoborate is filtered off, and the filtrate treated with the alcoholic solution of hydrofluosilicic acid.One mgrm. of sodium in 5 C.C. of 50 per cent. alcohol can be readily detected. For the detection of small amounts of sodium in presence of much potassium, the filtrate from the potassium fluoborate is evaporated, the residue ignited, taken up in 50 per cent.alcohol, and tested as described. G. C. J. Note by Abstractor.-In separating potassium by means of perehloric acid, said by the authors to be preferable where available, it should be noted that certain specimens of this acid, sold for analytical purposes, are liable to contain sodium (Thin and Cumming, J.Chm. Soc., 1915,107, 361). New Method of Estimating Sodium and Potassium in a Mixture of their Salts. K. Okada. (Mem. Coll. Science, Kyoto Imp. University, 1915, 1, No. 2; through Chem. News, 1915, 111, 300.)-On mixing sodium hydrogen tartrate with a solution of potasaium and sodium salts and keeping the temperature and volume of the liquid constant, the concentration of the tartrates remaining in solution is a function of the percentage of potassium present.Hence, by plotting this function as a curve and estimating the concentration of the tartrates left in solution, the composition of a mixture of sodium and potassium salts may be ascertained with approximate accuracy. In the author's experiments the standard curve was determined by dissolving 1 grm.of the mixed chlorides of known composition and 2.4 grms. of sodium hydrogen tartrate in water, diluting the solution to 50 c.c., and keeping it at 25" C. for five hours. A measured quantity (20 c.c.) of the clear liquid was then evaporated, the residue ignited at red heat, and the alkalis extracted with a measured quantity of standard hydrochloric acid, the excees of which was subsequentIy titrated.The quantity of acid required was placed on the ordinate and! the weight of sodium chloride on the abscissa axis of the curve. By means of this method the double sulphate of sodium and potassium has been found to have the formula, K*Na(SO,),. I t is soluble as a, solid solution in sodium sulphate, but not in potas- sium sulphate. C. A. M.INORGANIC ANALYSIS 369 Analysis of Spelter.W. B. Price and Others. (J. Ind. and Enq. Chem., 1915, 7, 547-548.)-A Report of a Sub-committee on Methods of Analysis of Non- ferrous Alloys of the American Chemical Society. The methods reoommended are those actually in use in the laboratories of the more important producers and consumers of zinc in the United States. Spelters are olassified as A , High Grade; B, Intermediate; C, Brass Special, and D, Prime Western, the last a low grade used chiefly for galvanising.Sampling.-A number of slabs should be sawn in half, and the sawdust used as the sample. Fine drillings may be used. In neither case should a lubricant be used, and the drillings must be freed from iron by magnets. Lend.-For the estimation of lead electrolytically, the sample (8.643 grms.) is covered with wafer in a 400 C.C.beaker, and 30 C.C. of nitric acid are then added gradually. The factor 8.643 differs from the theoretical factor (8.66) slightly, because lead dioxide cannot be dried completely. When action is complete, the solution is boiled to expel nitrous fumes, transferred to a 200 C.C. electrolytic beaker, diluted to 125 c.c., and electrolysed with a current of 5 amperes, Deposition is complete in thirty to forty-five minutes.To insure complete deposition, the covers and beaker are rinsed down with sufficient water to raise the level of the liquid 0.5 inch, and electrolysis continued for fifteen minutes. The newly exposed surface should remain bright. The anode is washed three or four times with distilled water, once with alcohol, and dried at 210° C.for thirty minutes. The number of decigrams of lead dioxide corresponds directly to the percentage of lead. The electrodes are cylinders of 20 mesh (per lineal cm.) platinum gauze. The anodes &re 30 mm. in diameter and 30 mm. high, the cathodes the same height, but only 18 mm. in diameter. Both have stems of stout wire 10 cm.long. In the absence of electrolytic appliances, lead is estimated as follows: The drillings (25, 15, 10, or 5 grms., according to grade) are treated with 300,180, 120, or 60 C.C. (according to weight of drillings) of “lead acid”-that is to say, dilute sulphuric acid saturated with lead sulphate, prepared by mixing 300 C.C. of con- centrated acid with 1,800 C.C. of water, and adding to the hot solution 300 C.C.of water in which 1 grm. of lead acetate has been dissolved. The “lead acid” thus prepared is allowed to settle several days and then filtered. After all but 1 grm. of zinc has dissolved, the solution is filtered, the undissolved residue washed with 6 4 lead acid,” then washed back into the beaker and dissolved in a small quantity of hot dilute (1 : 1) nitric acid. The resulting solution is evaporated with 40 0.0.(( lead acid” until fumes arise. When cool, 35 C.C. of water are added, boiled, the first filtrate containing most of the zinc and a trace of lead is added, and the mixture left over- night. The lead sulphate is filtered on a Gooch crucible, washed with (‘ lead acid,” then with dilute (1 : 1) alcohol, and finally with strong alcohol.The Gooch crucible is placed in a porcelain crucible and ignited for five minutes, The solution is boiled, diluted to 300 c.c., ammonium chloride (10 grms.) is added, and ammonia, in sufficient amount to redissolve the zinc hydroxide, The mixture is boiled and filtered through a 11 cm. I ‘ black ribbon” paper, which is washed with dilute ammonia and hot water. The ferric hydroxide is dissolved in hot, dilute (1 : 4) sulphnric acid, Irom-The zinc (25 grms.) is dissolved in 125 C.C. nitric acid.370 ABSTRACTS OF CHEMICAL PAPERS the solution passed through a Jones's reductor, which is washed with 150 C.C. of dilute sulphuric acid and 100 C.C. of water, the reduced solution being finally titrated with -&& permanganate. Using such dilute permanganate as this, it is essential to run a control with the same amounts of acid and water. Cadmium.-The drillings (25 grms.) are covered with 250 C.C. water and 55 C.C. hydrochloric acid and left overnight. More acid is added, 2 C.C. at a time, with an interval between each addition, so as to dissolve all but about 2 grms. of zinc with a minimum use of acid, about 60 C.C. in all usually sugcing. A piece of the undis- solved zinc is transferred to a filter, the liquid is filtered, and the undissolved matter is washed with water, rejecting filtrate and washings. The undissolved matter is dissolved in nitric acid, and the solution evaporated with 20 C.C. of dilute (1 : 1) sulphuric acid until fumes ariee. The residue is taken up with 100 C.C. of water, the mixture boiled and allowed to stand overnight. The lead sulphate is filtered off and discarded. The filtrate is diluted to 400 c.c., 10 grms. ammonium chloride are added, and the solution saturated with hydrogen sulphide (one hour). I t is sometimes necessary to add a drop or two of ammonia to start the precipitation of cadmium sulphide. The impure cadmium sulphide is filtered off on a Gooch crucible and dissolved in 60 C.C. (more if necessary) of dilute (1 : 5 ) sulphuric acid by boiling for thirty minutes. The solution is filtered from asbestos and lead sulphide, diluted to 300 C.C. and cadmium reprecipitated as sulphide in presence of 5 grms. ammonium chloride. When much cadmium is present, a third precipitation may be necessary. The precipitate is dissolved in hot dilute (1 : 3) hydrochloric acid in a platinum dish, the solution evaporated to fuming with sulphuric acid, diluted, any filter fibres destroyed by addition of nitric acid and heating, which is continued to dryness and finally to 500 to 600" C., or to dull redness, the cadmium being weighed as sulphate. An alternative electrolytic method for cadmium is described. G. C. J.